| Message ID | 1472026407-3448-2-git-send-email-mike.looijmans@topic.nl (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Wed, Aug 24, 2016 at 10:13:27AM +0200, Mike Looijmans wrote: > Add devicetree property for early initialization of the fan controller > to prevent overheating, for example when resetting the board while the > fan was completely turned off. > > Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> > --- > Documentation/devicetree/bindings/hwmon/max6650.txt | 5 +++++ > 1 file changed, 5 insertions(+) The kernel boot seems kind of late to ensure your fan is running, but Acked-by: Rob Herring <robh@kernel.org> -- To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 30-08-16 18:38, Rob Herring wrote: > On Wed, Aug 24, 2016 at 10:13:27AM +0200, Mike Looijmans wrote: >> Add devicetree property for early initialization of the fan controller >> to prevent overheating, for example when resetting the board while the >> fan was completely turned off. >> >> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> >> --- >> Documentation/devicetree/bindings/hwmon/max6650.txt | 5 +++++ >> 1 file changed, 5 insertions(+) > > The kernel boot seems kind of late to ensure your fan is running, but > > Acked-by: Rob Herring <robh@kernel.org> Thanks! Well, "late's better than never," my grandma used to say when we visited :) To put your mind at ease, the particular platform I'm using this for is an xc7z045 (Zynq) where the ARMs running the Linux kernel will only account for 0.5W, but once the logic awakens the chip can dissipate up to 30W. The logic bitstream is usually on the rootfs, so kernel boot is early enough for the fan to start spinning. And with the logic asleep, it need not spin at all.
diff --git a/Documentation/devicetree/bindings/hwmon/max6650.txt b/Documentation/devicetree/bindings/hwmon/max6650.txt index d6c10e3..f6bd87d 100644 --- a/Documentation/devicetree/bindings/hwmon/max6650.txt +++ b/Documentation/devicetree/bindings/hwmon/max6650.txt @@ -13,6 +13,10 @@ Optional properties, default is to retain the chip's current setting: - maxim,fan-prescale : Pre-scaling value, as per datasheet [1]. Lower values allow more fine-grained control of slower fans. Valid: 1, 2, 4, 8, 16. +- maxim,fan-target-rpm: Initial requested fan rotation speed. If specified, the + driver selects closed-loop mode and the requested speed. + This ensures the fan is already running before userspace + takes over. Example: fan-max6650: max6650@1b { @@ -20,4 +24,5 @@ Example: compatible = "maxim,max6650"; maxim,fan-microvolt = <12000000>; maxim,fan-prescale = <4>; + maxim,fan-target-rpm = <1200>; };
Add devicetree property for early initialization of the fan controller to prevent overheating, for example when resetting the board while the fan was completely turned off. Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> --- Documentation/devicetree/bindings/hwmon/max6650.txt | 5 +++++ 1 file changed, 5 insertions(+)